1. Field of the Invention
The present invention relates to an actuating head of a double-acting or lift and force pump for ejecting a product from a container. The actuating head includes an outlet duct leading to an ejection opening, wherein a valve closing piece is arranged in the outlet duct. Together with the outlet duct, the valve closing piece forms a check valve which, when the actuating head is actuated, is opened by the pressure of the product against the force of a spring and allows the product to flow into a space defined by the inner side of the outlet duct and the circumference of the valve closing piece. This space is connected through at least one transverse groove to the ejection opening. The valve closing piece is of a rubber-elastic material which is elastically deformed by the product pressure when the actuating head is actuated and opens the check valve, wherein the valve closing piece borders with its end face against the at least one transverse groove and rests with its rear side against a radially inwardly protruding shoulder of the outlet duct.
2. Description of the Related Art
An actuating head of the above-described type is disclosed in DE 694 09 380 T2. In this actuating head, the valve closing piece is axially compressed by the fluid pressure when the actuating head is actuated and the valve closing piece is lifted by the radially inwardly protruding shoulder of the outlet duct. Lifting of the valve closing piece by the radially inwardly protruding shoulder requires a high actuating pressure and a high actuating force. Consequently, when the pump is used for the first time, the actuating head must be actuated several times in order to build up the required high pressure. This is cumbersome. A high actuating force may also have to be applied by the user.
DE 26 44 321 A shows an actuating head in which a fitting piece is arranged between the ejection opening and the valve closing piece, wherein the fitting piece covers the transverse grooves leading to the ejection opening. The valve closing piece rests on the fitting piece through a restoring spring. The valve closing piece is cup-shaped and is of a hard material. When the head is actuated, the valve closing piece is displaced from a closed position in the outlet duct in which it sealingly rests against the inner side of the outlet duct into the open position against the force of the restoring spring. During this displacement, the valve closing piece slides along axial ribs formed on the inner side of the outlet duct. The ribs define grooves through which the product can flow to the transverse grooves. The restoring spring protrudes into the interior space of the cup-shaped valve closing piece. Accordingly, the space between the ejection opening and the valve closing piece in the closed position has a relatively large volume. A correspondingly large product quantity remains in this space after the actuation of the head. Moreover, ambient air is drawn into the space during the return movement of the valve closing member into the closed position. Consequently, the product quantity remaining in the space may become contaminated. This may lead to significant health problems if the product is a foodstuff or a medicament, for example, a medicament which is applied onto the skin, for example, a wound, of a patient or which is to be sprayed into the mouth of a patient.
It is the primary object of the present invention to provide an actuating head of the above-described type in which the actuating pressure required for opening the check valve is lower.
In accordance with the present invention, the rear side of the valve closing piece is provided with at least one radial groove and the portion of the outlet duct located on the rear side of the valve closing piece can be connected through the at least one radial groove to the space, wherein the valve closing piece has a circumferential sealing lip which releases the flow of the product as a result of the product pressure when the actuating head is actuated.
As a result of the configuration according to the present invention, it is not necessary that the entire valve closing piece is being deformed. Rather, only the sealing lip of the valve closing piece has to be deformed. This can be achieved with low pressure.
In contrast to the actuating head according to DE 26 44 321 A, a separate restoring spring for the valve closing piece and a fitting piece between the restoring spring and the ejection opening for covering the at least one transverse groove are not required. As a result, not only the manufacture of the actuating head is less complicated, but the distance between the valve closing piece and the outlet opening in the closed position of the valve closing piece and, consequently the volume of the space therebetween, can be reduced. As a result, after actuating the actuating head, a smaller amount of product remains in the space in which the product could be contaminated, so that the danger of health problems is also reduced.
In accordance with a preferred feature, the valve closing piece elastically rests with its rear side against the radially inwardly protruding shoulder of the outlet duct. This makes it unnecessary to displace the valve closing piece and to provide space for making the movement possible. The space between the valve closing piece and the ejection opening can then also be smaller.
In accordance with a preferred feature, the valve closing piece is of solid material. This eliminates a hollow space in the valve closing piece.
In addition, the outlet duct may extend through a pipe which laterally protrudes beyond the circumference of the container, wherein the ejection opening is provided in the form of a nozzle at the free end of the pipe. This pipe makes it possible to place the ejection opening close to the location where the product is intended to impinge, for example, into the mouth of a patient, without being impeded by the container, so that the danger of a contamination of the product as it travels from the ejection opening to the application location is essentially avoided.
The sealing lip preferably surrounds the valve closing piece approximately in the axial middle thereof. This reduces the space between the sealing lip and the ejection opening further. The remaining product quantity which remains in the space and could come into contact with the ambient air is then also reduced.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.